SYNTHESIS AND CHARACTERIZATION OF 3,6-DIAMINOACRIDINE (PROFLAVINE) CONTAINING POLYIMIDES

The tricyclic heterocyclic molecule 3,6-diaminoacridine (proflavine) h as been reacted with the dianhydrides pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-(hexaf luoroisopropylidene) diphthalic anhydride (6FDA), and naphthalenetetra carboxylic dianhydride (NTCDA) to yield a new series of polyimides in which the aromatic tricyclic clic component contains a ring nitrogen a tom at position 10. The synthesis of the four polymers was achieved wi thin; the temperature range of 185-195 degrees C and each of the polyi mides was characterized with respect to solubility, thermal-properties ; infrared and W-visible spectra, refractive index, and permittivity. Uniform, light yellow films of the four polyimides could be cast from appropriate solvents. TGA analysis of these polyimides showed that the y were thermally stable up to 600 degrees C in a nitrogen atmosphere. These polymers exhibited low permittivity values and high refractive i ndices. All four;polymers were soluble in dilute formic acid, in addit ion to several common organic solvents. Formic acid solutions of the p olyimide from 3,3',4,4'-benzophenonetetracarboxylic dianhydride and pr oflavine exhibited birefringent behavior. upon orientation by repeated passage through a viscometer capillary. In contrast to the polymer pr epared from 3,7-diaminophenothiazine (thionine) and pyromellitic dianh ydride, in which the intermediate poly(amic acid) could be isolated nd characterized, the reaction of proflavine and pyromellitic dianhydrid e did not proceed at sufficiently low temperatures to permit the isola tion of the intermediate poly(amic acid).